Energy evolution of brittle granite under different loading rates

Abstract

The mechanisms for rock failure involve instability, where an energy exchange and transformation occurs between the rock and an external energy source. Few studies have been conducted on rock failure characteristics in terms of the energy evolution under different loading rates. This study investigated the damage resulting from brittle granite failure under loading rates of 0.001, 0.005, 0.01, and 0.05 mm/s from the energy perspective. The results showed that the elastic and scattered strain energies absorbed in the initial compression phase were small. The elastic strain energy absorbed in the rock elasticity stage was mainly stored in the form of elastic energy, and the rate of increase for the scattered energy was less than those for the total strain energy and elastic strain energy. In the dilatation and breaking stage, the scattered energy increased sharply, elastic energy was rapidly released, and rock bursting accompanied the breaking. The loading rate increased from 0.001 mm/s to 0.05 mm/s, total strain energy increased by 91%, elastic energy increased by 48%, and spread energy increased by 184%. At the first stage of loading, the damage variable of the rock mass was small. With an increase in the loading rate, the damage variable of the rock sample gradually increased. When the stress reached its peak value, the damage variable rapidly increased. Under the same stress, a greater loading rate resulted in a greater change in the damage variable.